In printers, where there is a capability of feeding multiple sheets, the sheets must be fed to the printer in such a manner as to not overlap the pages. This gap control may be handled in one of several different ways. One technique is to stage the paper or feed the sheet to a known reference point near the printing mechanism and abut the paper against a stop. When the appropriate moment occurs, to feed the sheet to the printing mechanism, the gate or stop is withdrawn and the sheet fed. This staging inherently extends the interpage gap and reduces the throughput of the printer.
An alternate approach to the staging of the paper is to continuously feed the sheets but at a speed and spacing that even with page to page length variations and variations in the feed speed of different sheets, the gap is sufficiently large as to prevent the overlapping of the adjacent sheets or the reduction of the gap to a point that the machine detects a condition that it cannot distinguish from a paper jam, requiring that the printer be shut down. When the gap is enlarged to accommodate the worst case condition, the effective throughput of the printer is severely degraded since the print mechanism is idle for periods significantly in excess of that necessary for reliable operation.
It is desirable to minimize the gap spacing, consistent with the printer design to eliminate undesired idle time.
At the same time, it is important that the gap between sheets not be narrowed too severely and the controls of the paper feed system be misled into recognizing conditions that would otherwise indicate a paper jam, thereby requiring the printer to be shut down and the operator to clear the condition and restart the machine.